Hi,
We are introducing a kernel driver for hardware spinlock, called hwspinlock.
It is designed to interface with the OMAP4 hardware spinlock module. This
driver supports:
- Reserved spinlocks for internal use
- Dynamic allocation of unreserved locks
- Lock, unlock, and trylock functions, with or without disabling irqs/preempt
- Registered as a platform device driver
The device initialization will set aside some spinlocks as reserved for
special-purpose use. All other locks can be used by anyone. This is
configurable using a Kconfig option. The device initialization file is:
arch/arm/mach-omap2/hwspinlocks.c
The driver takes in data passed in device initialization. The function
hwspinlock_probe() initializes the array of spinlock structures, each
containing a spinlock register address provided by the device initialization.
The device driver file is:
arch/arm/plat-omap/hwspinlock.c
Here's an API summary:
int hwspinlock_lock(struct hwspinlock *);
Attempt to lock a hardware spinlock. If it is busy, the function will
keep trying until it succeeds. This is a blocking function.
int hwspinlock_trylock(struct hwspinlock *);
Attempt to lock a hardware spinlock. If it is busy, the function will
return BUSY. If it succeeds in locking, the function will return
ACQUIRED. This is a non-blocking function
int hwspinlock_unlock(struct hwspinlock *);
Unlock a hardware spinlock.
int hwspinlock_lock_irqsave(struct hwspinlock *, unsigned long *);
Same as hwspinlock_lock, but disables interrupts and preemption
int hwspinlock_trylock_irqsave(struct hwspinlock *, unsigned long *);
Same as hwspinlock_trylock, but disables interrupts and preemption
int hwspinlock_unlock_irqrestore(struct hwspinlock *, unsigned long);
Same as hwspinlock_unlock, but restores interrupts and preemption
struct hwspinlock *hwspinlock_request(void);
Provides for "dynamic allocation" of an unreserved hardware spinlock.
If no more locks are available, returns NULL.
struct hwspinlock *hwspinlock_request_specific(unsigned int);
Provides for "static allocation" of a reserved hardware spinlock. This
allows the system to use a specific reserved lock, identified by an ID.
If the ID is invalid or if the desired lock is already allocated, this
will return NULL.
int hwspinlock_free(struct hwspinlock *);
Frees an allocated hardware spinlock (either reserved or unreserved).
Please see the below patch contents, or the attached patch, and provide feedback.
Signed-off-by: Simon Que <sque@xxxxxx>
Cc: Hari Kanigeri <h-kanigeri2@xxxxxx>
=====================================================================
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index 9f73d79..a13c188 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -182,3 +182,13 @@ config OMAP3_SDRC_AC_TIMING
wish to say no. Selecting yes without understanding what is
going on could result in system crashes;
+config OMAP_HWSPINLOCK_NUM_RESERVED
+ int "Number of hardware spinlocks reserved for system use"
+ depends on ARCH_OMAP
+ default 8
+ range 0 32
+ help
+ Choose a number of hardware spinlocks to reserve for internal use.
+ The rest will be unreserved and availble for general use. Make
+ that the number of reserved locks does not exceed the total number
+ available locks.
diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index 6725b3a..14af19a 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -170,3 +170,5 @@ obj-y += $(nand-m) $(nand-y)
smc91x-$(CONFIG_SMC91X) := gpmc-smc91x.o
obj-y += $(smc91x-m) $(smc91x-y)
+
+obj-y += hwspinlocks.o
\ No newline at end of file
diff --git a/arch/arm/mach-omap2/hwspinlocks.c b/arch/arm/mach-omap2/hwspinlocks.c
new file mode 100644
index 0000000..de813a0
--- /dev/null
+++ b/arch/arm/mach-omap2/hwspinlocks.c
@@ -0,0 +1,126 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments. All rights reserved.
+ *
+ * Contact: Simon Que <sque@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#include <plat/hwspinlock.h>
+
+/* Base address of HW spinlock module */
+#define HWSPINLOCK_BASE (L4_44XX_BASE + 0xF6000)
+#define HWSPINLOCK_REGADDR(reg) \
+ OMAP2_L4_IO_ADDRESS(HWSPINLOCK_BASE + (reg))
+
+/* Spinlock register offsets */
+#define HWSPINLOCK_REVISION 0x0000
+#define HWSPINLOCK_SYSCONFIG 0x0010
+#define HWSPINLOCK_SYSSTATUS 0x0014
+#define HWSPINLOCK_LOCK_BASE 0x0800
+
+/* Spinlock register addresses */
+#define HWSPINLOCK_REVISION_REG \
+ HWSPINLOCK_REGADDR(HWSPINLOCK_REVISION)
+#define HWSPINLOCK_SYSCONFIG_REG \
+ HWSPINLOCK_REGADDR(HWSPINLOCK_SYSCONFIG)
+#define HWSPINLOCK_SYSSTATUS_REG \
+ HWSPINLOCK_REGADDR(HWSPINLOCK_SYSSTATUS)
+#define HWSPINLOCK_LOCK_REG(i) \
+ HWSPINLOCK_REGADDR(HWSPINLOCK_LOCK_BASE + 0x4 * (i))
+
+/* Spinlock count code */
+#define HWSPINLOCK_32_REGS 1
+#define HWSPINLOCK_64_REGS 2
+#define HWSPINLOCK_128_REGS 4
+#define HWSPINLOCK_256_REGS 8
+#define HWSPINLOCK_NUMLOCKS_OFFSET 24
+
+
+/* Initialization function */
+int __init hwspinlocks_init(void)
+{
+ int i;
+ int retval = 0;
+
+ struct platform_device *pdev;
+ struct hwspinlock_plat_info *pdata;
+ void __iomem *base;
+ int num_locks;
+ bool is_reserved;
+
+ /* Determine number of locks */
+ switch (__raw_readl(HWSPINLOCK_SYSSTATUS_REG) >>
+ HWSPINLOCK_NUMLOCKS_OFFSET) {
+ case HWSPINLOCK_32_REGS:
+ num_locks = 32;
+ break;
+ case HWSPINLOCK_64_REGS:
+ num_locks = 64;
+ break;
+ case HWSPINLOCK_128_REGS:
+ num_locks = 128;
+ break;
+ case HWSPINLOCK_256_REGS:
+ num_locks = 256;
+ break;
+ default:
+ return -EINVAL; /* Invalid spinlock count code */
+ }
+
+ /* Device drivers */
+ for (i = 0; i < num_locks; i++) {
+ pdev = platform_device_alloc("hwspinlock", i);
+
+ base = HWSPINLOCK_LOCK_REG(i); /* Get register address */
+
+ /* Some locks are reserved for system use */
+ if (i < CONFIG_OMAP_HWSPINLOCK_NUM_RESERVED)
+ is_reserved = true;
+ else
+ is_reserved = false;
+
+ /* Pass data to device initialization */
+ pdata = kzalloc(sizeof(struct hwspinlock_plat_info),
+ GFP_KERNEL);
+ pdata->num_locks = num_locks;
+ pdata->io_base = base;
+ pdata->is_reserved = is_reserved;
+ retval = platform_device_add_data(pdev, pdata, sizeof(*pdata));
+ if (retval)
+ goto device_add_fail;
+
+ retval = platform_device_add(pdev);
+ if (retval)
+ goto device_add_fail;
+ continue;
+device_add_fail:
+ platform_device_put(pdev);
+ }
+
+ return retval;
+}
+module_init(hwspinlocks_init);
+
diff --git a/arch/arm/plat-omap/Makefile b/arch/arm/plat-omap/Makefile
index a37abf5..fb98ff9 100644
--- a/arch/arm/plat-omap/Makefile
+++ b/arch/arm/plat-omap/Makefile
@@ -32,4 +32,5 @@ obj-y += $(i2c-omap-m) $(i2c-omap-y)
obj-$(CONFIG_OMAP_MBOX_FWK) += mailbox.o
obj-$(CONFIG_OMAP_REMOTE_PROC) += remoteproc.o
-obj-$(CONFIG_OMAP_PM_NOOP) += omap-pm-noop.o
\ No newline at end of file
+obj-$(CONFIG_OMAP_PM_NOOP) += omap-pm-noop.o
+obj-y += hwspinlock.o
\ No newline at end of file
diff --git a/arch/arm/plat-omap/hwspinlock.c b/arch/arm/plat-omap/hwspinlock.c
new file mode 100644
index 0000000..327a524
--- /dev/null
+++ b/arch/arm/plat-omap/hwspinlock.c
@@ -0,0 +1,331 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments. All rights reserved.
+ *
+ * Contact: Simon Que <sque@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <plat/hwspinlock.h>
+
+/* for managing a hardware spinlock module */
+struct hwspinlock_state {
+ bool is_init; /* For first-time initialization */
+ int num_locks; /* Total number of locks in system */
+ spinlock_t local_lock; /* Local protection */
+};
+
+/* Points to the hardware spinlock module */
+static struct hwspinlock_state hwspinlock_state;
+static struct hwspinlock_state *hwspinlock_module = &hwspinlock_state;
+
+/* Spinlock object */
+struct hwspinlock {
+ void __iomem *io_base;
+ bool is_reserved;
+ bool is_allocated;
+ struct platform_device *pdev;
+};
+
+/* Array of spinlocks */
+static struct hwspinlock *hwspinlocks;
+
+/* API functions */
+
+/* Busy loop to acquire a spinlock */
+int hwspinlock_lock(struct hwspinlock *handle)
+{
+ int retval;
+
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ if (WARN_ON(in_atomic() || in_irq()))
+ return -EPERM;
+
+ /* Attempt to acquire the lock by reading from it */
+ do {
+ retval = __raw_readl(handle->io_base);
+ } while (retval == HWSPINLOCK_BUSY);
+
+ return 0;
+}
+EXPORT_SYMBOL(hwspinlock_lock);
+
+/* Attempt to acquire a spinlock once */
+int hwspinlock_trylock(struct hwspinlock *handle)
+{
+ int retval = 0;
+
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ if (WARN_ON(in_atomic() || in_irq()))
+ return -EPERM;
+
+ /* Attempt to acquire the lock by reading from it */
+ retval = __raw_readl(handle->io_base);
+
+ return retval;
+}
+EXPORT_SYMBOL(hwspinlock_trylock);
+
+/* Release a spinlock */
+int hwspinlock_unlock(struct hwspinlock *handle)
+{
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ /* Release it by writing 0 to it */
+ __raw_writel(0, handle->io_base);
+
+ return 0;
+}
+EXPORT_SYMBOL(hwspinlock_unlock);
+
+/* Busy loop to acquire a spinlock, disabling interrupts/preemption */
+int hwspinlock_lock_irqsave(struct hwspinlock *handle, unsigned long *flags)
+{
+ int retval;
+ unsigned long temp_flags;
+
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ if (WARN_ON(in_atomic() || in_irq()))
+ return -EPERM;
+
+ if (WARN_ON(flags == NULL))
+ return -EINVAL;
+
+ /* Attempt to acquire the lock by reading from it */
+ do {
+ preempt_disable(); /* Disable preemption */
+ local_irq_save(temp_flags); /* Disable interrupts */
+
+ retval = __raw_readl(handle->io_base);
+
+ /* Restore interrupts and preemption if not successful */
+ if (retval == HWSPINLOCK_BUSY) {
+ local_irq_restore(temp_flags);
+ preempt_enable();
+ }
+ } while (retval == HWSPINLOCK_BUSY);
+
+ *flags = temp_flags; /* Return IRQ state */
+
+ return 0;
+}
+EXPORT_SYMBOL(hwspinlock_lock_irqsave);
+
+/* Attempt to acquire a spinlock once, disabling interrupts/preemption */
+int hwspinlock_trylock_irqsave(struct hwspinlock *handle, unsigned long *flags)
+{
+ int retval = 0;
+ unsigned long temp_flags;
+
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ if (WARN_ON(in_atomic() || in_irq()))
+ return -EPERM;
+
+ if (WARN_ON(flags == NULL))
+ return -EINVAL;
+
+ preempt_disable(); /* Disable preemption */
+ local_irq_save(temp_flags); /* Disable interrupts */
+
+ /* Attempt to acquire the lock by reading from it */
+ retval = __raw_readl(handle->io_base);
+
+ /* Restore interrupts and preemption if not successful */
+ if (retval == HWSPINLOCK_BUSY) {
+ local_irq_restore(temp_flags);
+ preempt_enable();
+ } else
+ *flags = temp_flags; /* Return IRQ state */
+
+ return retval;
+}
+EXPORT_SYMBOL(hwspinlock_trylock_irqsave);
+
+/* Unlock a spinlock that was locked with irq/preempt disabled */
+int hwspinlock_unlock_irqrestore(struct hwspinlock *handle, unsigned long
+ flags)
+{
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ /* Release it by writing 0 to it */
+ __raw_writel(0, handle->io_base);
+
+ /* Restore interrupts and preemption */
+ local_irq_restore(flags);
+ preempt_enable();
+
+ return 0;
+}
+EXPORT_SYMBOL(hwspinlock_unlock_irqrestore);
+
+/* Request an unclaimed spinlock */
+struct hwspinlock *hwspinlock_request(void)
+{
+ int i;
+ bool found = false;
+ struct hwspinlock *handle = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&hwspinlock_module->local_lock, flags);
+ /* Search for an unclaimed, unreserved lock */
+ for (i = 0; i < hwspinlock_module->num_locks && !found; i++) {
+ if (!hwspinlocks[i].is_allocated &&
+ !hwspinlocks[i].is_reserved) {
+ found = true;
+ handle = &hwspinlocks[i];
+ }
+ }
+ spin_unlock_irqrestore(&hwspinlock_module->local_lock, flags);
+
+ /* Return error if no more locks available */
+ if (!found)
+ return NULL;
+
+ handle->is_allocated = true;
+
+ return handle;
+}
+EXPORT_SYMBOL(hwspinlock_request);
+
+/* Request an unclaimed spinlock by ID */
+struct hwspinlock *hwspinlock_request_specific(unsigned int id)
+{
+ struct hwspinlock *handle = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&hwspinlock_module->local_lock, flags);
+
+ if (WARN_ON(!hwspinlocks[id].is_reserved))
+ goto exit;
+
+ if (WARN_ON(hwspinlocks[id].is_allocated))
+ goto exit;
+
+ handle = &hwspinlocks[id];
+ handle->is_allocated = true;
+
+exit:
+ spin_unlock_irqrestore(&hwspinlock_module->local_lock, flags);
+ return handle;
+}
+EXPORT_SYMBOL(hwspinlock_request_specific);
+
+/* Release a claimed spinlock */
+int hwspinlock_free(struct hwspinlock *handle)
+{
+ if (WARN_ON(handle == NULL))
+ return -EINVAL;
+
+ if (WARN_ON(!handle->is_allocated))
+ return -ENOMEM;
+
+ handle->is_allocated = false;
+
+ return 0;
+}
+EXPORT_SYMBOL(hwspinlock_free);
+
+/* Probe function */
+static int __devinit hwspinlock_probe(struct platform_device *pdev)
+{
+ struct hwspinlock_plat_info *pdata = pdev->dev.platform_data;
+ int id = pdev->id;
+
+ /* Set up the spinlock count and array */
+ if (!hwspinlock_module->is_init) {
+ hwspinlock_module->num_locks = pdata->num_locks;
+
+ /* Allocate spinlock device objects */
+ hwspinlocks = kmalloc(sizeof(struct hwspinlock) *
+ hwspinlock_module->num_locks, GFP_KERNEL);
+ if (WARN_ON(hwspinlocks == NULL))
+ return -ENOMEM;
+
+ /* Initialize local lock */
+ spin_lock_init(&hwspinlock_module->local_lock);
+
+ /* Only do initialization once */
+ hwspinlock_module->is_init = true;
+ }
+
+ hwspinlocks[id].pdev = pdev;
+
+ hwspinlocks[id].is_reserved = pdata->is_reserved;
+ hwspinlocks[id].is_allocated = false;
+ hwspinlocks[id].io_base = pdata->io_base;
+
+ return 0;
+}
+
+static struct platform_driver hwspinlock_driver = {
+ .probe = hwspinlock_probe,
+ .driver = {
+ .name = "hwspinlock",
+ },
+};
+
+/* Initialization function */
+static int __init hwspinlock_init(void)
+{
+ int retval = 0;
+
+ /* Register spinlock driver */
+ retval = platform_driver_register(&hwspinlock_driver);
+
+ /* Make sure the it was properly initialized */
+ if (WARN_ON(!hwspinlock_module->is_init))
+ return -EACCES;
+
+ return retval;
+}
+
+/* Cleanup function */
+static void __exit hwspinlock_exit(void)
+{
+ platform_driver_unregister(&hwspinlock_driver);
+
+ /* Free spinlock device objects */
+ if (hwspinlock_module->is_init)
+ kfree(hwspinlocks);
+}
+
+module_init(hwspinlock_init);
+module_exit(hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver");
+MODULE_AUTHOR("Simon Que");
+MODULE_AUTHOR("Hari Kanigeri");
diff --git a/arch/arm/plat-omap/include/plat/hwspinlock.h b/arch/arm/plat-omap/include/plat/hwspinlock.h
new file mode 100644
index 0000000..1cdf7a8
--- /dev/null
+++ b/arch/arm/plat-omap/include/plat/hwspinlock.h
@@ -0,0 +1,35 @@
+/* hwspinlock.h */
+
+#ifndef HWSPINLOCK_H
+#define HWSPINLOCK_H
+
+#include <linux/platform_device.h>
+#include <plat/omap44xx.h>
+
+/* Read values from the spinlock register */
+#define HWSPINLOCK_ACQUIRED 0
+#define HWSPINLOCK_BUSY 1
+
+/* Device data */
+struct hwspinlock_plat_info {
+ int num_locks; /* Number of locks (initialization) */
+ void __iomem *io_base; /* Address of spinlock register */
+ bool is_reserved; /* Reserved for system use? */
+};
+
+struct hwspinlock;
+
+int hwspinlock_lock(struct hwspinlock *handle);
+int hwspinlock_trylock(struct hwspinlock *handle);
+int hwspinlock_unlock(struct hwspinlock *handle);
+
+int hwspinlock_lock_irqsave(struct hwspinlock *handle, unsigned long *flags);
+int hwspinlock_trylock_irqsave(struct hwspinlock *handle, unsigned long *flags);
+int hwspinlock_unlock_irqrestore(struct hwspinlock *handle, unsigned long
+ flags);
+
+struct hwspinlock *hwspinlock_request(void);
+struct hwspinlock *hwspinlock_request_specific(unsigned int id);
+int hwspinlock_free(struct hwspinlock *hwspinlock_ptr);
+
+#endif /* HWSPINLOCK_H */
--
1.7.0
Attachment:
0001-omap-hwspinlock-Added-hwspinlock-driver.patch
Description: 0001-omap-hwspinlock-Added-hwspinlock-driver.patch
